package mianxiangduixiang.Week2;

import java.util.Scanner;

public class Distance {

    public static void main(String[] args) {
        System.out.println(distance());
    }

    private static String distance() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("?????????x1 x2 y1 y2??");
        int x1 = scanner.nextInt();
        int x2 = scanner.nextInt();
        int y1 = scanner.nextInt();
        int y2 = scanner.nextInt();
        int dis1, dis2;
        if (x2 > x1)
            dis1 = x2 - x1;
        else dis1 = x1 - x2;
        if (y2 > y1)
            dis2 = y2 - y1;
        else dis2 = y1 - y2;
        return Math.sqrt((dis1*dis1)+(dis2*dis2))+"";
    }
}
